U.S. Pat. No. 3,379,278, issued Apr. 23, 1968, discloses a muffler for use on a pneumatic tool such as a grinder. An open-ended sleeve of an elastic, resilient material is tightly fitted over the body portion and exhaust ports of the tool, being bonded to the body portion. Spent air exhausted from the tool forces the sleeve away from the tool and escapes at the end of the sleeve. A band of non-elastic material is placed around the body of the tool closely adjacent the exhaust ports in the opposite direction from the end of the sleeve through which the air escapes. This band is secured to the sleeve and prevents air from forcing the sleeve away from the body portion of the tool.
U.S. Pat. No. 3,993,159, issued Nov. 23, 1976, discloses a muffler for reducing the noise level of the air exhaust from a governed pneumatic tool. The muffler, which is formed of plastic or metal, is secured to the tool housing by screws and forms an enclosed cavity extending about the exhaust apertures of the tool. A foraminous baffle plate, which in the disclosed embodiment is a thin brass screen, is located within the cup-shaped body of the muffler.
U.S. Pat. No. 4,496,023, issued Jan. 29, 1985, discloses a plastic silencer surrounding a compressed air tool in the form of a pneumatically operated impact tool. The silencer forms an exhaust chamber about the tool. Two exhaust tubes project from the chamber and holes are drilled near the inlet ends of the tubes to prevent ice build up.
U.S. Pat. No. 3,255,844, issued Jun. 14, 1966, discloses a multi-passage silencer for pneumatic tools of the percussion type. The silencer is specifically adapted to and devised for permanent attachment to a tool of that type.
U.S. Pat. No. 3,719,251, issued Mar. 6, 1973, relates to a diffuser for employment with portable pneumatic tools such as a dentist drill to disperse exhausted air.
A search directed to the present invention also located the following U.S. Pat. Nos.: 4,367,807, issued Jan. 11, 1983, 3,447,630, issued Jun. 3, 1969, 2,019,697, issued Nov. 5, 1935, and 2,996,139, issued Aug. 15, 1961.